When you're single, flirtation can be a harmless pastime. As long as you and your flirt friend are on the same page, then it's fun to engage in a little banter now and then. Once you're in a committed relationship, however, flirting can feel more like a threat. But you can usually spot these flirtationships before they become a real problem by knowing the signs your spouse is flirting with other people.

Now it must be said that the definition of appropriate and inappropriate flirting will vary a bit for every relationship. Some people may be flattered when outsiders express an interest in their partner, while others will feel threatened when their partner's gaze lingers on someone else for too long. It's all about knowing your own comfort zone, communicating that to your parter, and trusting that your SO will respect your boundaries. As long as everything is above-board and no one gets unreasonably possessive or jealous, then the boundaries for flirting can be easy enough to establish.

That said, relationships ebb and flow over time, and the boundaries you and your SO once adhered to firmly may start to become less defined. But by recognizing the signs your partner is getting flirty with others, you can address any concerns before they turn into full-blown problems.

1. They're Shady With The Phone


If your SO suddenly has a new lockscreen code and gets secretive about texts, then your partner may have an overly flirty text buddy. According to the Huffington Post, when someone starts texting in secret, or even deleting texts, then it's a good sign they aren't totally appropriate for some reason or other. Hopefully you can have a conversation about this and sort it out.

2. They Have Wandering Eyes


Sure, you and your SO are still living, breathing people, and everyone sneaks a peak at attractive strangers now and then. But if your partner openly gawks at others while out with you, it may be a sign that they're OK with disrespecting your boundaries, as noted in Baggage Reclaim. How do you think they act when you aren't around?

3. They Have A Newly Polished Appearance


Maybe your partner just wants the confidence boost that comes along with dressing better. But the Huffington Post noted that if your SO suddenly starts looking sharp for certain other people, then you may want to call a time-out. It may mean your partner is flirting with someone else — possibly more.

4. They Are Touchy-Feely


For many people, it can be difficult to tell the difference between flirting and just being nice. But getting touchy-feely with others is a pretty undeniable form of flirting, as Love Panky noted. Unless you're already in an open relationship, then this is probably cause for a serious chat.

5. They Act Differently With Different People


If your partner is pretty neutral to everyone, but lights up when interacting with a particular person or persons, then this may be a clue. As explained in Truth About Deception, when flirty behavior becomes person specific, it may be headed in the "this is a problem" direction. Pay attention if your spouse shows special interest to a particular friend.

6. They Have Sexualized Behavior


What constitutes inappropriate flirting will vary from couple to couple. Many couples draw the line at sexualized behavior that feels like betrayal, as noted in Psychology Today. For some couples that line may be dancing with another man; for others, it may be full-on physical affection.

7. They Spend A Lot Of Time Online Chatting


Online chatting can make it difficult to spot flirting. As explained in Pop Sugar, if one partner has an online life that includes virtual flirting, then this may lead to problems IRL. Whether the SO is chatting up a coworker all day or talking to Orcs on WoW, you may want to have a chat about what's appropriate in that realm.

8. Someone Else Voices Concern


Sometimes friends can spot the red flags before you can. As explained in Psych Central, if a trusted friend voices concern about an SO's flirty friendship, then you probably want to listen up. Good friends will have your back.

9. You Have A Gut Feeling


Sometimes you don't have any evidence, but your gut just tells you something is up. This may be a sign that you and your partner need to have a conversation about trust and boundaries.